原子力显微镜高次谐波幅度对样品弹性性质表征的研究

轻敲模式下原子力显微镜微悬臂探针在接近其基态共振频率的外加驱动下振荡, 其末端针尖周期性靠近、远离样品, 产生于针尖与样品非线性相互作用过程中的高次谐波信号包含更多的待测样品表面纳米力学特性等方面的信息. 通过理论分析、计算, 系统地研究了针尖与样品接触时间受样品弹性模量的影响, 以及高次谐波幅度与接触时间的关系, 获得了通过高次谐波幅度区分待测样品表面弹性性质差异的规律. 并在自制的高次谐波成像实验装置上, 得到了与理论预期一致的实验结果. 关键词： 轻敲模式原子力显微镜 接触时间 高次谐波幅度 弹性模量

Characterization of elastic properties of a sample by atomic force microscope higher harmonic amplitude

When the atomic force microscope cantilever in tapping-mode is vibrated at a frequency close to its fundamental resonance frequency, the tip on its free end will be close to and away from the sample periodically. The higher harmonic signals produced by non-linear interactions between the tip and sample surface contain more nanomechanical information. We study the influence on the contact time by different elastic modulus and the relationship between higher harmonic amplitude and contact time. By theoretical analysis and calculation, we obtain the law of characterizing the sample surface elastic difference with the higher harmonic amplitude. Moreover, we obtain the experimental result consistent with the theory, on our homemade higher harmonic system.
Keywords： tapping-mode atomic fore microscope contact time higher harmonic amplitude elastic modulus